During the last decades, several types of bindings for cross-country skiing have been suggested and published. However, many of those bindings have not been used for various reasons. One reason for problems is that the skiing boots/shoes and the bindings in the skies shall be matched by construction type with each other, meaning that the boot manufacturing company, the binding manufacturing company, and the ski manufacturing company must have close cooperation. Another problem is that the users may want to buy new boots for their old skis, or new skis for their old boots. This means that the new binding models should work with boots and skis of older models. This, on the other hand, brings the problem of accumulated features that are necessary in boots, skis and bindings in order to ensure compatibility with older models.
Most prior art bindings use a connection at the very front end of the boot. This solution does not allow optimally ergonomic movement of the users foot. The front connection does not either provide user's accurate control of the ski. Additionally, there have been other technical problems and/or lack in ease of use in the prior art bindings.
Prior art document US 2007/0138765 A1 discloses a cross-country ski binding device that retains the front end of a cross-country ski boot, the rear end of the boot remaining free to be raised and lowered. For this purpose the ski assembly comprises: a ski having an upper surface adapted to receive a binding device to retain a boot on the ski; a binding device to retain at least a front end of a boot against detachment from the ski, said binding device comprising an anchoring device for anchoring the binding device to the ski, said anchoring device comprising a slide, and a tightening mechanism for enabling a flattening of a lower part of the binding device against the upper surface of the ski.
In the binding device of the document the front connector is adapted to cooperate with a locking mechanism having a movable hook-shaped jaw and a transverse edge forming all immovable jaw for locking the boot onto the sports apparatus, or ski. Once locked in the locking mechanism, the front connector can freely pivot inside the jaw, thus allowing for an articulated binding of the front end of the boot. In this mentioned document the binding device is adapted to ensure the binding of a cross-country ski boot having two-part connectors, whereupon the boots has two connectors, such as rods or pins or other structural elements, arranged in the boot sole so as to be flush beneath the latter, or substantially flush. Therefore, these connectors are, for example, two cylindrical connectors extending across a longitudinal groove provided in the lower surface of the sole of the boot. The front connector is arranged, for example, in the vicinity of the front end of the sole, and the rear connector is rearwardly offset by a predetermined distance, so as to be arranged in the area of, or forward of, a zone of the boot corresponding to the metatarsophalangeal zone of the user's foot. The arrangement of the connecting zones enables the skier, when using a boot having a flexible sole, to maintain a flexing of the boot that corresponds to the flexing of the foot.
Document EP 0 725 578 B1 discloses a cross-country ski shoe/boot consisting of an upper joined to a sole and of which the sole has a means of fixing and hinging to the upper surface of the waist of a ski, this means being located close to the front end of the sole, whereupon the lower surface of the sole also has a second means of fixing located in the area between the heel and the metatarsal-phalangeal joint capable of co-operating with a matching means of fixing located on the upper surface of the waist of the ski. Further the first means of fixing consists of a shaft that is transversal with respect to the longitudinal direction of the ski, and the second means of fixing consists of a transverse shaft that is parallel to shaft and located in the same longitudinal direction of the shoe, each means of fixing being accommodated in a separate recess made in the outer surface of sole.
The document also discloses a cross-country ski unit using the mentioned shoe, the ski unit comprising a ski and a binding which may or may not be integral with the ski. This binding comprises: device suitable for cooperating with and retaining the first means of fixing of the shoe and capable of sliding in a direction that is parallel to the longitudinal direction of the ski, and a means of control placed in front of the binding intended to make said device slide in order to engage it in or release it from the first means of fixing of the shoe; whereupon the binding has a second device intended to cooperate with and retain the second means of fixing on the sole of the shoe located between the area of the heel and the metatarsal-phalangeal joint.
Although the solutions disclosed in these prior art documents reduce effects of some of the problems described above, the solutions are still not optimal. For example, the distance between the user's foot and the ski bottom is too high in order to allow accurate control of the ski. Also, the described solutions are not optimized for both skating type skiing and classic type skiing